<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>

    <style type="text/css">
        *{
            margin: 0;
            padding: 0;
        }

        .main{
            width: 100%;
            height: auto;
            background: grey;
            margin: 0 auto;
            overflow: hidden;

        }

        /*高度塌陷*/
        .main div{
            width: 20%;
            min-width: 200px;
            height: 200px;
            background: blue;
            float: left;
            border: 1px solid white;
            padding: 20px;
            box-sizing: border-box;


        }

        .main-box{
            width: 90%;
            height: auto;
            background: #7e804f;
            margin: 0 auto;
            display: flex;
            flex-direction: row;
            flex-wrap: wrap;

        }
        .main-box div:first-child{
            flex: 1;
            height: 200px;
            min-width: 200px;
            background: pink;
        }

        .main div{
            min-width: 200px;
        }
        .main-box div:nth-child(2){
            flex: 1;
            min-width: 200px;
            height: 200px;
            background: #bf16ff;
        }
        .main-box div:nth-child(3){
            flex: 1;
            min-width: 200px;
            height: 200px;
            background: #a1ff6f;
        }

        .main-box div:nth-child(4){
            flex: 1;
            min-width: 200px;
            height: 200px;
            background: #5dff8a;
        }
        .footer{
            width: 90%;
            height: 120px;
            background: gainsboro;
            margin: 0 auto;
        }
    </style>
</head>
<body>


    <div class="main">
        <div>
            div01
        </div>
        <div></div>
        <div></div>
        <div></div>
    </div>

    <div class="main-box">
        <div>

        </div>
        <div></div>
        <div></div>
        <div></div>
    </div>

    <div class="footer">

    </div>
</body>
</html>